1. Field of the Invention
The present invention relates to a color ink composition, particularly an ink composition suitable for use in ink jet recording, and an ink jet recording method using the same.
2. Background Art
In the formation of a color image using an ink composition, particularly in the formation of a color image by using an ink jet recording method, it is common practice to use at least a magenta ink, a yellow ink, and a cyan ink. Properties required of such inks include: stability of the ink under storage conditions such that the composition and properties of the ink do not undergo any change in composition and properties; stability of the ink such that the nozzles of the print head do not become clogged; and suitable property values of the ink, such as viscosity and surface tension; capability of the ink to provide an image possessing a high optical density; capability of the ink to provide sharp tone and image; excellent fastness, for example, excellent waterfastness and lightfastness; freedom from odor; and good safety.
Many of these property requirements have been satisfied by an aqueous ink comprising a water-soluble dye dissolved in water or a mixed system of water and a water-soluble solvent.
Properties, such as tone, waterfastness, and lightfastness, are greatly depend on dyes used, leading to various studies on the dyes.
For example, C.I. Acid Yellow 17 and 23 are known as a yellow dye having a high water solubility. The high water solubility of these dyes are less likely to cause clogging of nozzles. However, the problems of waterfastness and lightfastness have remained unsolved.
Japanese Patent Laid-Open No. 96967/1984 discloses the use of C.I. Direct Yellow 86, 100, and 142 having good lightfastness. So far as the present inventors know, however, these dyes have a fear of nozzles being clogged. Further, with these dyes, it is difficult to provide a sharp tone. Japanese Patent-Laid Nos. 306075/1988 and 28690/1988 disclose the formation of a color image using a yellow dye represented by the formula (VII) which is one of the dyes used in the present invention, and the claimed advantage of this method is that a good color image can be provided. According to an experiment conducted by the present inventors, however, there is still room for an improvement in the prevention of clogging and the realization of a sharp tone. Further, there is room for an improvement in the storage stability of prints prepared with the dye. In particular, on a specialty paper, having a coating, for ink jet recording, the dye bleeds due to moisture in the environment, causing the image to be blurred.
Regarding a magenta composition, it has been pointed out that a deterioration in prints is mostly attributable to magenta. As compared with a yellow ink composition, a cyan ink composition, and a black ink composition, the magenta ink composition exhibits more significant fading, leading to a change in tone of the printed image. Further, when the print is allowed to stand under an environment having high humidity, the feathering of magenta occurs, resulting in deteriorated quality of the printed image.
Further, in color printing using a plurality of ink compositions, similar properties are required of all the ink compositions used. When one ink composition is poor in a certain property, the dignity of the whole image is lost.
One of the color image forming methods is to conduct overprinting using three colors of yellow, magenta, and cyan ink compositions to realize red, green, and blue. Black may be prepared with overprinting all the yellow, magenta, and cyan ink compositions or with printing a black ink individually provided. In the color image forming methods, the ink compositions, as such, each should have a good tone and, at the same time, when overprinted, should exhibit a good tone.
Further, an ink composition has bee desired which can realize a good printed image, especially a printed image having excellent waterfastness and a good tone, on recording media, i.e., on specialty paper having a coating, as well as on pain paper.